Introduction to

Post-Harvest
Handling
 Biological aspects of
Post-Harvest Handling

TOPICS

a. General characteristics of fruits, vegetables

b. Quality evaluation of perishables

 Objectives

After the completion of the chapter, students

will be able to:

1. Discuss the characteristics of fruit and

vegetables
2. Determine the methods of quality evaluation
in perishables
General Characteristics of Fruits and Vegetables

1. Botanical Classifications
2. Morphological And Anatomical Basis For
Perishability Of Fruits And Vegetables
3. Physiological Basis For Perishability Of Fruits
And Vegetables
4. Biochemical Changes
FRUITS are defined as the
Botanical
mature ovary of a flower
Classifications
containing seeds

VEGETABLES are classified

by the edible part of the plant,
such as roots, stems, leaves,
flowers, and bulbs Botanical
Classifications
 Fruits
➢Simple Fruits

➢Aggregate Fruits

➢Multiple Fruits
Picture reference: https://orbisec.com/fruit-salad-part-i/
 SIMPLE FRUITS
Fleshy Fruits:
➢ Drupe: Peaches, cherries, olives
➢ Berry: Tomatoes, grapes, bananas
➢ Pome: Apples, pears

Dry Fruits:
➢ Dehiscent: Peas, beans, poppies (these fruits split open
at maturity to release seeds)

➢ Indehiscent: Nuts (like acorns and hazelnuts), grains

(such as wheat and corn)
Photo reference: https://www.vedantu.com/question-answer/an-aggregate-fruit-is-the-one-which-develops-class-11-biology-cbse-
5f8a7c732331d1505cd0f4f1
AGGREGATE FRUITS

➢ Raspberry
➢ Blackberry
➢ Strawberry
➢ Boysenberry
Photo reference:
https://slideplayer.com/slide/8795449/
 Vegetables

•Roots
•Stems
•Leaves
•Flowers
•Bulbs
CLASSIFICATION OF FOOD CROPS
BASED ON THEIR POSTHARVEST LIFE

1. PERISHABLES are food crops

whose food value is maintained
over a short period of time after
harvest.
CLASSIFICATION OF FOOD CROPS
BASED ON THEIR POSTHARVEST LIFE

2. DURABLES are food crops

which can be maintained as
food over a long period of time.
Morphological and Anatomical
Basis for Perishability of Fruits
and Vegetables
 What is the difference
between Morphology and
Anatomy?
Morphology refers to the form and structure of the fruits
and vegetables, including external and surface features.
 Anatomy

refers to the internal

structure and organization
of cells and tissues within
the fruits and vegetables.
Morphological Basis of Perishability
Morphological
Basis of
Perishability

1. Surface Characteristics
2. Fruit and Vegetable Shape and
Structural Integrity
3. Size and Surface Area-to-Volume
Ratio:
Surface
Characteristics:
a. Cuticle Thickness and
Composition:
b. Presence of Trichomes
c. Stomata and Lenticels
Density
d. Laticifers
 1. Surface Characteristics:
a. Cuticle Thickness and Composition:

• The cuticle is the non-cellular waxy layer above the epidermal cells of
the commodity.

• The epidermal cells comprise the first layer of the cells exposed to
the environment.
• The cuticle serves as a protective barrier that influences water retention
and susceptibility to microbial invasion.
• Its thickness and chemical makeup vary among species and stages of
maturity.
Grapes and Tomatoes Orange and Apple
b. Presence of Trichomes

These hair-like structures can offer

protection against pests and aid in reducing
water loss but may also harbor pathogens
under certain conditions.
c. Stomata and Lenticels Density

The distribution and density of these gas-

exchange pathways can increase the risk of
dehydration and pathogen entry, affecting
storage longevity.
• As the cuticle develops during full development and
maturation some of the stomata get covered.

• Immature fruits have more stomata than mature

ones which partially explains why immature fruits
deteriorate faster.

• Pechay has 13,000 stomates per cm2 in the lower

surface of one leaf and possibly twice as much for
both surfaces.
Presence of
laticifers
2. Fruit and Vegetable Shape and Structural Integrity
• The shape and structural resilience impact bruising
susceptibility during handling and transportation.
 3. Size and Surface Area-to-Volume Ratio
• These dimensions influence how quickly moisture
is lost and how heat is distributed, affecting
spoilage rates.

• The greater the surface area to volume ratio, the

faster the diffusion of gases involved in respiration,
exit of water through transpiration and entry of
microorganisms and chemicals
Morphological
Basis of
Perishability

1. Surface Characteristics
2. Fruit and Vegetable Shape and
Structural Integrity
3. Size and Surface Area-to-Volume
Ratio:
 Anatomy

refers to the internal

structure and organization
of cells and tissues within
the fruits and vegetables.
 Anatomical Basis
of Perishability

• involves several critical structural

and biochemical factors.
• Each of these factors contributes
uniquely to the degradation
processes that occur post-harvest.
 Anatomical Basis
of Perishability

1. Cellular Structure
2. Respiration and Metabolic
Activity
3. Ethylene Sensitivity and
Production
1. Cellular Structure

a. Cell Wall Composition

b. Intercellular Spaces
c. Water Content and
Vascular Structure
 a. Cell Wall Composition

• The rigidity and integrity of the cell wall are

determined by the composition and arrangement of
cellulose, hemicellulose, and pectin.

• As fruits ripen, enzymatic breakdown of pectin leads

to softening, making them more susceptible to
physical damage and microbial attack
 b. Intercellular Spaces

• Intercellular spaces are vital for facilitating gas exchange,

allowing for the exchange of oxygen, carbon dioxide, and
ethylene. Variability in these spaces impacts the rate of
respiration and the spread of spoilage organisms.
• Fruits and vegetables with larger intercellular spaces, like
apples, can experience a more rapid spread of decay when
breached by pathogens due to facilitated gas and
microorganism diffusion.
 c. Water Content and Vascular Structure
• High water content is crucial for maintaining turgor pressure,
which affects texture and firmness. However, it also makes
tissues more prone to microbial growth and enzymatic activity.
• The arrangement and functionality of vascular tissues (xylem and
phloem) affect the distribution of water and nutrients, impacting
wilting and spoilage post-harvest.
• Efficient water management and rapid post-harvest cooling are
strategies employed to mitigate these risks.
 What is the difference
between RESPIRATION
and TRANSPIRATION?
 TRANSPIRATION

RESPIRATION
 2. Respiration and Metabolic Activity
• Respiration is the process by which stored carbohydrates
are broken down with the aid of oxygen to release energy,
carbon dioxide, and water.
• High respiration rates leading to faster nutrient depletion
and spoilage.
• Storage conditions such as controlled atmosphere storage
(lower oxygen levels) are commonly used to decelerate
these processes.
Commodities with low respiration rates are storage
organs.

Ex. Onions, potato, gabi, sweet potato, yams and ginger.

Respiration date as about 1.52 mg CO2/kg/ha
 Commodities with
intermediate rates are
exemplified by many fruits
at physiological maturity.

The respiration rate of

lanzones is 70 mg
CO2/kg/ha.
Commodities with high rates are organs at immature
stage.

Ex: asparagus, snap beans, cauliflower, okra, young

corn, bean sprouts. the respiration rate is 570.6 mg
CO2/kg/ha at 26 degrees centigrade.
 3. Ethylene Sensitivity and Production

• Ethylene (C2H4) is a hormone in gas form which causes the

acts as a ripening hormone, accelerating senescence and
spoilage in many fruits and vegetables.

• The timing and extent of its production can vary, with climacteric
fruits like bananas experiencing a significant spike in ethylene
production post-harvest, leading to rapid ripening.

• Strategies to mitigate ethylene effects include using ethylene

blockers like 1-MCP (1-methylcyclopropene) or employing
ethylene scrubbers in storage facilities.
STRATEGIES TO
REDUCE PERISHABILITY

Temperature
Management

• Refrigeration slows
down respiration and
metabolic processes,
reducing spoilage rates.
STRATEGIES TO
REDUCE PERISHABILITY

Controlled Atmosphere
Storage
Modifying atmospheric
composition (oxygen,
carbon dioxide) in
storage environments
can slow respiration
and ethylene effects.
STRATEGIES TO
REDUCE PERISHABILITY

Edible Coatings
• Used to extend the shelf life of fruits
and vegetables by providing a thin
layer of material that can reduce
moisture loss, delay ripening, and
protect against microbial
contamination
• They are selected based on the
specific needs and characteristics of
the produce being treated.
STRATEGIES TO
REDUCE PERISHABILITY Edible Coatings
a. Waxes
b. Chitosan
c. Aloe Vera Gel
d. Starch-based Coatings
e. Protein-based Coatings
f. Lipid-based Coatings
g. Pectin-based Coatings
h. Alginate-based Coatings
i. Carrageenan
 STRATEGIES TO
REDUCE PERISHABILITY
4. Breeding and Genetic
Modification

Developing varieties
with thicker cuticles,
enhanced cell wall
strength, or reduced
ethylene production
can improve shelf life.
 STRATEGIES TO
REDUCE PERISHABILITY
5. Physical and
Chemical
Treatments

Use of treatments like

heat shock, irradiation,
or chemical sanitizers
can kill or inhibit
microbial growth.
 Physiological Basis For
Perishability Of Fruits And
Vegetables
 Physiology
It focuses on
understanding the
mechanisms that enable
organisms to maintain life,
from the molecular and
cellular levels to tissues,
organs and entire system.
Plant Physiology
It focuses on the functioning
of plants and the biological
process that allow them to
grow, reproduce and
survive.
-nutrient absorption
-water transport
-photosynthesis and
respiration
- Hormone regulation
What are the key differences
between plant’s morphology,
anatomy, and physiology?
 MORPHOLOGY
- looks at the external form and physical features of
plants

ANATOMY
-examines the internal structure and organization of
tissues and cells

PHYSIOLOGY
-studies functional processes and biochemical activities
that sustain plant life.
 Physiological Basis For Perishability Of
Fruits And Vegetables

1. Physiological Process
2. Physiological Changes
3. Physiological Characteristics
 PHYSIOLOGICAL PROCESS
• The functional activities or changes that occur within a living
organism or its parts to maintain life.
• These processes are fundamental to growth, development, and
adaptation, and they operate at various levels, from cellular to whole-
organism scales.
• In plants, physiological processes include photosynthesis, respiration,
transpiration, nutrient uptake, and fruit ripening, among others.
• These processes can be influenced by internal factors like hormones
and external factors such as temperature and light.
 PHYSIOLOGICAL CHANGES

• refer to the biochemical and physical transformations

that occur within an organism during its growth,
development, maturation, and post-harvest phases.

• These changes can significantly affect the quality,

appearance, taste, and shelf life of agricultural
commodities such as fruits and vegetables.
 PHYSIOLOGICAL CHANGES

1. Ripening: In fruits, ripening involves the softening of texture,

sweetening as starches convert to sugars, and changes in color due
to chlorophyll breakdown and the synthesis of pigments like
carotenoids and anthocyanins.

2. Senescence: The process of aging in plant tissues, leading to the

degradation of chlorophyll, decline in photosynthetic efficiency, and
eventual cell death.
 PHYSIOLOGICAL CHANGES

3. Post-Harvest Respiration: Continued metabolic activity

where oxygen is consumed, and carbon dioxide is
produced, influencing the degradation rate of the
commodity.

4. Ethylene Production: A hormone-induced process

promoting ripening and senescence, affecting both the
harvested commodity and surrounding produce.
 PHYSIOLOGICAL CHARACTERISTICS

• Inherent attributes of an organism that dictates its

function and behavior within a biological context.

• These characteristics are generally stable over time but

can vary among species or even cultivars within a species.
 RESPIRATION RATE
➢ This process involves the
consumption of oxygen and
the production of carbon
dioxide, water, and heat.

➢ Generally, higher respiration

rates lead to faster
deterioration and a loss of
quality, resulting in quicker
spoilage.
 2. ETHYLENE PRODUCTION
➢Ethylene is a gaseous plant hormone that regulates a range of
developmental processes, including ripening and senescence.

➢ Ethylene Sensitivity: The degree to which a plant or plant part

responds to ethylene exposure, affecting its ripening and
senescence rate.
➢Impact: Many fruits generate this natural hormone, which
accelerates ripening and senescence, impacting their storage
and transportation methods.
 Ethylene Absorbers

Zeolite Potassium Permanganate Ozone Generators

Silica Gel with

Clay Minerals Potassium Permanganate Activated Carbon
 3. WATER CONTENT, TURGOR PRESSURE AND TRANSPIRATION

➢ Water Content
Refers to the amount of water present in the fruit or
vegetable.

• Importance: Water content affects texture, flavor, and

overall freshness. High water content is generally
associated with crispness and juiciness.
 3. WATER CONTENT, TURGOR PRESSURE AND TRANSPIRATION

➢ Turgor Pressure
• The pressure exerted by the fluid (water) inside the cell against
the cell wall.

• Importance: Turgor pressure helps maintain the structural

integrity of plant cells, contributing to the firmness of fruits and
vegetables. Loss of turgor pressure can lead to wilting and loss
of quality.
 3. WATER CONTENT, TURGOR PRESSURE AND TRANSPIRATION

➢ Water Loss
• The process by which water evaporates from the surface of fruits
and vegetables.

• Importance: Excessive water loss can lead to dehydration,

resulting in shriveling and a decline in quality. It can also affect
weight and marketability.
 3. WATER CONTENT, TURGOR PRESSURE AND TRANSPIRATION

➢ Transpiration
• The process by which water is absorbed by plant roots and then
evaporates from the aerial parts, primarily through stomata.

• Importance: Transpiration is a natural process that can lead to

water loss in post-harvest produce. It plays a role in nutrient
transport but can also contribute to wilting and spoilage if not
managed properly.
 4. SENESCENCE

• The final stage of development in which the commodity

undergoes degradative processes leading to aging and death of
plant cells.

• Effects: It involves the breakdown of cell components, leading

to loss of texture, color, and nutritional quality.

• Delay Tactics: Optimal storage conditions and treatments with

anti-senescent agents can slow down senescence.
 5. NUTRIENT AND FLAVOR CHANGES

• Vitamin Loss:
Post-harvest, some vitamins, particularly Vitamin C, are
susceptible to degradation due to exposure to light, heat,
and oxygen.

• Flavor Compounds:
Biochemical changes can lead to the development or
loss of key flavor and aromatic compounds.
Technologies and Practices for Managing Physiological Processes

COLD STORAGE
Reduces respiration rates and
delays senescence.
 Technologies and Practices for Managing Physiological Processes

Modified Atmosphere Packaging (MAP)

Adjusts the levels of oxygen and carbon dioxide in packaging to slow down
respiration and ethylene activity.
 Technologies and Practices for Managing Physiological Processes

Use of Ripening
Inhibitors

Chemicals like
1-Methylcyclopropene
(1-MCP) are used to
inhibit ethylene
perception, slowing
down ripening.
 Technologies and Practices for Managing Physiological Processes

Humidity Control

Ensures that
moisture levels are
kept optimal to
prevent
dehydration and
maintain freshness.